Program for Sustainable Pavement Engineering and Research

About the research

About 74% of Iowa’s 89,000-mile road network consists of gravel roads (Iowa County Engineers Association 2018). These roads provide the fabric for rural life and livelihood in Iowa by linking agricultural producers with markets, and rural residents with their communities. The fact that these surfaces must be renewed as often as every three years imposes financial stress on county highway departments.

Coarse aggregates (CA) are a major constituent of granular surfaces and are known to undergo both physical and chemical changes due to weather and traffic that affect their properties and ultimately, their longevity. Despite the importance of these roads to the economic fabric of Iowa and their need for constant upkeep, we lack a robust understanding of not only the deterioration mechanisms that are most responsible for CA break down, but we also do not know the geological factors that make one CA perform better than another.

This study aims to characterize the changes that occur in these coarse aggregates by characterizing changes in the geological fabric and properties of coarse aggregates from both in service roads and laboratory specimens. Using this information, highway engineers and geologists can act in the fiduciary interest of taxpayers to minimize costs while providing a safe and reliable transportation network for rural communities and producers.